The present invention relates generally to a flexible web dispenser that includes a powered, hands-free web transfer mechanism and, more particularly, to a paper towel dispenser having a automatic, power transfer mechanism for introducing a primary towel roll into a towel feeding mechanism and for transferring the feed supply of a paper towel dispenser from a primary roll to a reserve roll upon the sensed exhaustion of the primary roll.
Industrial dispensers are widely used in public lavatories for dispensing paper towels to users. These dispensers can be designed to dispense either rolled paper towel sheets or folded paper towels arranged in a linear bundle. Rolled paper towels are continuous webs of paper toweling that are wound around a central core and, upon dispensing, are separated into and delivered as individual lengths of material. Folded towels are individual lengths of a paper web that have been pre-cut, folded into a predetermined configuration and arranged in a vertical or horizontal bundle for being individually dispensed.
Rolled paper towel dispensers typically include a user operated crank or lever that drives a feed mechanism to dispense the paper towels. However, as can be appreciated, these dispensers can also include an automatically operated feed mechanism as disclosed in copending U.S. Pat. applications Ser. Nos. 09/081,637 and 09/453,794 to Formon et al. titled xe2x80x9cPaper Towel Dispenserxe2x80x9d which are hereby expressly incorporated by reference. The automatic feed mechanism includes a drive roller and a pressure roller, also known as a pinch roller, which form a nip. When the rolled paper runs out in a conventional roll dispenser, an attendant must replace the roll(s) and manually insert the leading edge of the rolled towel into the nip. This can require complex towel threading and complicated loading sequences. After the attendant has placed the leading edge of the roll into the nip, the feed mechanism is operated in order to advance the leading edge through the feed mechanism, unwind the paper towel from the roll core and deliver the paper towel to the user. The feed mechanism can be either manual or automatic.
In contrast to folded paper towel dispensers, there is no economical way to replenish a roll towel dispenser when only a portion of the reserve roll, or xe2x80x9cstubxe2x80x9d roll, remains within the dispenser. In some prior art dispensers, a new roll must be substituted for the stub roll, thereby wasting whatever paper remains on the stub. This can result in increased operational costs as a significant amount of paper maybe be wasted in facilities with many dispensers. To overcome the problem of stub roll waste, roll dispensers have been designed to dispense two rolls of web material sequentially such that upon depletion of a primary roll, feeding from a reserve roll is commenced.
Prior art systems have included different types of transfer systems to change between the primary and reserve rolls. One such transfer system uses the diameter of the primary roll as a gauge for activating a transfer mechanism when it reaches a predetermined size. U.S. Pat. No. 5,294,192 to Omdoll et al. discloses a system which includes a mechanical sensor that detects the amount of paper towel on a primary roll. When the primary roll is depleted to a predetermined level, the sensor mechanically activates a transfer apparatus which drives the free end of the reserve roll into the nip of a dispenser using a transfer bar. However, since the sensor detects the size of the primary roll, not the end of the rolled web, the reserve web may begin dispensing prior to the complete exhaustion of the primary roll. Thus, for a period of time, paper towel is simultaneously dispensed from both rolls. This results in wasted paper towels. Additionally, these types of mechanical sensors can become stuck within the dispenser and fail to operate.
To overcome these disadvantages, the systems of U.S. Pat. No. 4,165,138 to Hedge et al., U.S. Pat. No.4,611,768 to Voss, et al., and U.S. Pat. No. 4,378,912 to Perrin et al. provide a transfer mechanism which is based on the feed rolls themselves. These systems utilize a transfer mechanism which senses the absence or presence of paper from around a feed roll. In one system, this is accomplished by a sensing finger which rides along the top surface of the web material and then drops down into a groove in the feed roll which is exposed when the trailing end of the primary web has been unwound from the roll. In response to the sensing finger moving into the groove, the reserve web is introduced into the feed nip between the drive roller and the pressure roller, and the dispenser begins to feed the reserve roll to the user. This type of transfer mechanism generally eliminates the false transfers associated with tension responsive systems and reduces the amount of double sheet dispensing which occurs in diameter sensing transfer systems. The use of sensing fingers on the web material, however, produces extra friction which can inadvertently tear the web. Moreover, the introduction of additional components to sense the absence of the web and transfer the reserve web to between the feed rollers creates opportunities for a transfer failure to occur.
The object of the present invention is to overcome the drawbacks of the prior art paper towel dispensers.
It is also an object of the present invention to provide a web dispenser that includes a powered web transfer mechanism which eliminates the need for an attendant to feed a leading edge of a rolled web into the nip.
It is further an object of the present invention to provide a web dispenser having a powered web transfer mechanism that automatically and reliably feeds a leading edge of a reserve roll into a nip.
The present invention relates to a paper towel dispenser which provides hands free, automatic feeding of the first sheet of a primary web roll, such as a paper towel roll, into a feed mechanism when its cover is closed. The dispenser also automatically transfers its web feed supply from a primary roll to a reserve roll upon the exhaustion of the primary roll. The present invention eliminates the need for an attendant to thread the leading edge of a primary or reserve roll into the feed mechanism of the dispenser. The dispenser also eliminates wasted paper because it does not begin to feed the reserve roll until the primary roll has expired.
The dispenser includes a chassis having a web discharge opening and a feed mechanism for advancing the web to the web discharge opening. The dispenser can include either a manual feed mechanism or a powered feed mechanism. The dispenser also includes a sensor for determining when a portion of the web is absent from a side of the feed mechanism proximate the web discharge opening. When such an absence is sensed, an automatic, powered web transfer mechanism contacts the web located in front of the feed mechanism and positions it between the rollers of the feed mechanism. The transfer mechanism includes a web transfer member and a motor for driving the transfer member in the direction of the feed mechanism. The dispenser also includes a retraction mechanism for returning the transfer bar to a rest position after the web has been introduced into the feed mechanism.
A method of positioning a web in a feed mechanism of a dispenser according to the present invention includes the steps of positioning a leading edge of a web proximate a first side of the feed mechanism, sensing the absence of the web on a second side of the feed mechanism and activating a powered transfer drive mechanism in response to the sensed absence. The method further includes the steps of automatically advancing a transfer bar in the direction of the feed mechanism when the drive mechanism is activated, engaging the web with a plurality of web positioning members on the transfer bar and advancing the web into the feed mechanism.